Floor panel

ABSTRACT

A floor may include a substrate having a top side and a bottom side. A top layer may be provided on the substrate. The top layer may consist of a printed thermoplastic film and a thermoplastic transparent or translucent layer provided on the printed thermoplastic film. The top layer may be directly adhered to the substrate by heat welding the printed thermoplastic film and the top side of the substrate, in the absence of a glue layer. The substrate may be a synthetic material board including a filler. The substrate at least at two opposite edges may include coupling means provided in the synthetic material board. The thermoplastic transparent or translucent layer may be provided with a structure.

This application is a continuation application of U.S. patentapplication Ser. No. 15/695,163, filed Sep. 5, 2017, which is acontinuation of U.S. patent application Ser. No. 15/045,389 filed Feb.17, 2016, now U.S. Pat. No. 9,783,995 issued Oct. 10, 2017, which is acontinuation application of U.S. patent application Ser. No. 14/015,307filed Aug. 30, 2013, now U.S. Pat. No. 9,322,184 issued Apr. 26, 2016,which is a divisional application of U.S. patent application Ser. No.13/696,769 filed Nov. 7, 2012, now U.S. Pat. No. 8,549,807 issued Oct.8, 2013, which is a US National Phase application of InternationalApplication No. PCT/IB2011/051884 filed Apr. 28, 2011, the entirecontent of all which are incorporated herein by reference.

This application claims priority under 35 USC § 119(a)-(d) to BelgianPatent Application No. 2010/0283 filed May 10, 2010, the entire contentof which is incorporated herein by reference.

BACKGROUND 1. Field

This invention relates to floor panels and methods for manufacturingfloor panels.

More particularly, the invention relates to floor panels of the typewhich is at least composed of a substrate and a top layer provided onthis substrate, wherein said top layer comprises a motif. As known,above said motif a transparent or translucent synthetic material layercan be provided, which layer then forms part of said top layer.

In particular, the present invention relates to floor panels of the typewhich, at two or more opposite edges, comprises coupling means orcoupling parts, with which two of such floor panels can be coupled atthe respective edges, such that they are locked together in a horizontaldirection perpendicular to the respective edge the floor panels, as wellas in a vertical direction perpendicular to the plane of the floorpanels. Such floor panels can be applied for composing a so-calledfloating floor covering, wherein the floor panels are interconnected attheir edges, however, are lying freely on the underlying floor.

2. Related Art

From WO 97/47834, laminate floor panels are known for forming a floatingfloor covering. However, laminate floor panels show the disadvantagethat they mostly are provided with a moisture-sensitive substrate,namely MDF or HDF (Medium Density Fiberboard or High DensityFiberboard), and that the top layer provided on said substrate, when thefloor covering is in use, leads to the development of ticking noises.Mostly, laminate floor panels have a thickness situated between 6 and 12millimeters, wherein the thickness of the top layer mostly is less than0.5 millimeters. Moreover, the high density of the substrate materialleads to high impact sensitivity.

From EP 1 290 290, it is known to provide laminate floor panels with astructured surface, for example, with a structure imitating wood pores.According to EP 1 290 290, such structure can be provided by means of apress device of the short-cycle type and an associated structured presselement or press platen. Herein, the structure can be provided in such amanner that it corresponds to the pattern of the laminate floor panels.

From EP 1 938 963, vinyl-based floor panels are known for forming suchfloating floor covering. Such vinyl-based floor panels mostly have athickness of 3 to 5 millimeters and have a high material density.Inherent to these floor panels is their limited bending stiffness andtheir high deformability. These features lead to problems when the floorpanels are applied on an uneven underlying surface. Namely, after acertain period of time the unevennesses of the underlying surface maymigrate to the surface of the floor covering. With a local load, forexample, underneath the legs of tables or chairs, permanent impressionswill occur, which are undesired as well. Such floor panels also lead toproblems with the propagation of sound towards underlying rooms.

SUMMARY

The present invention relates to an alternative panel, which inparticular is intended as a floor panel for forming a floating floorcovering. According to various preferred embodiments of the invention,also a solution is offered for one or more problems with the floorpanels of the state of the art.

To this aim, the invention, according to its first independent aspect,relates to a floor panel of the type which comprises at least asubstrate and a top layer provided thereon, wherein said top layercomprises a motif, with the characteristic that said substratesubstantially consists of a foamed synthetic material layer, whichpreferably has an average density of more than 300 kilograms per cubicmeter. In that a foamed synthetic material layer is applied, a lessmoisture-sensitive floor panel is obtained than in the case of an MDF orHDF substrate. By foaming, with a comparable amount of syntheticmaterial as with the floor panels of EP 1 938 963, a thicker and stiffersubstrate is obtained, such that the risk of the occurrence of migrationeffects from the underlying layer to the surface of the floor coveringcan be minimized. This is in particular the case when an average densityis applied of more than 300 kilograms per cubic meter. Said substratepreferably has a thickness of more than five millimeters. With suchthickness of the substrate, the risk of the occurrence of said migrationeffects is minimized even further. The minimum thickness of fivemillimeters also allows that sturdy mechanical coupling means can beformed in one piece with the synthetic material board, for example, inthat those can be provided at least partially directly in the syntheticmaterial board as milled profiles.

The preferred minimum average density of the foamed synthetic materialboard is also advantageous when providing, more particularly milling,the profiles and can result in coupling means offering a strong verticaland/or horizontal locking. With said minimum density, it is avoided thatthe edges of the synthetic material board are deformed too much. Boardsof a lower density namely have a higher risk of pushing up the edges,wherein such pushed-up edges will protrude above the actual boardsurface. Such effect is undesired. Another advantage of said minimumdensity is that it results in a better resistance against local loads.

Preferably, said synthetic material board has an average density of 450to 900 kilograms

per cubic meter, preferably 500 to 600 kilograms per cubic meter. It isclear that the above-mentioned advantages of the preferred minimumdensity are more pronounced with a higher density of the foamed boardmaterial. However, too high a density will lead to disadvantageouseffects, such as high impact sensitivity and increased sensitivity forpossible unevennesses in the underlying surface, whereby sound boxes canbe created, which effect an amplification of possible sound developedduring the use of the floor covering.

Preferably, said synthetic material board has a local density on one orboth flat sides which is higher than in a central layer of the foamedsynthetic material board. With such construction, an optimal combinationof an average low density and sufficient dimensional stiffness can beobtained. The locally higher density, preferably at least 5 or 10percent higher than the average density, of course can be situated onthe surface itself, as well as at a certain distance underneath thesurface of the respective side, however, at a distance from a centrallayer of the substrate. In the cases where the locally higher densitysubstantially is realized on one of both flat sides only, thispreferably relates to the side of the substrate which is situatedclosest to said top layer. By means of such embodiment, the risk of theoccurrence of permanent impressions can be minimized, while the floorpanel as a whole has a low weight.

Preferably, said foamed synthetic material board relates to a foamed PVC(polyvinyl chloride) board, or a foamed synthetic material board whichsubstantially consists of another vinyl compound, such as polyvinyldichloride, polyvinyl butyrate, polyvinyl acetate and the like. As analternative, as a basis material for the substrate use can also be madeof melamine foam, polyurethane or polyisocyanurate.

According to a particular embodiment, said foamed synthetic materialboard is of the closed cell type, still better it relates to a closedcell foamed PVC board. It is known as such that with foamed syntheticmaterial of the closed cell type the chambers of the foam practicallyare not interconnected, or at least to a much lesser extent than this isthe case with foamed synthetic materials of the open cell type. A foamedsynthetic material board of the closed cell type offers a very highstiffness, dimensional stability and water-resistance, with a limiteddensity of, for example, 600 kilograms per cubic meter or less. Thelimited density offers interesting advantages in logistics, such as intransport. Also, the limited density offers a more ergonomic whole, when5 to 10 of such floor panels are offered together in a packaging unit.It is clear that the present invention also relates to such packagingunit. The package applied therewith as such preferably consists at leastof a cardboard box or open-top box, and shrink film. For example, thepackaging materials can be applied which are known as such from WO2006/103565.

As also mentioned above, an average density of the synthetic materialboard situated between 500 and 600 kilograms per cubic meter leads to anoptimum result of all advantageous and disadvantageous effects. Suchdensity can be realized by means of synthetic materials of the closedcell type, such contrary to the usual hard foams of the open cell type,for example, polyester hard foams or the hard foams known from U.S. Pat.No. 3,853,685, which have a density of 150 kilograms per cubic meter orless and typically are applied for cushions or mattresses.

According to another embodiment, said synthetic material board comprisesseparate layers which increase the bending stiffness thereof. Suchlayers preferably are situated at a distance of the center of saidsynthetic material board, preferably at both sides of this center. Suchlayers can consist, for example, of a glass fiber cloth or glass fiberfabric. Preferably, this particular embodiment is combined with alocally higher density on one or both flat sides, as also mentionedabove.

Preferably, said top layer substantially consists of synthetic material.For example, said top layer can consist substantially of a vinylcompound or of a polyurethane compound. Preferably, said motif herein isformed by a printed synthetic material film, for example, a printed PVCfilm or a printed PUR (polyurethane) film. However, the invention doesnot exclude that the pattern can be formed in another manner, forexample, by means of a print performed directly on said substrate, or ona primer layer provided on this substrate. The top layer preferably alsoincludes a transparent or translucent layer based on synthetic materialand situated above the motif, which layer is provided as a film, whetheror not together with said printed film, or is provided in liquid formand subsequently is hardened on the substrate.

Preferably, the adherence between the top layer and the substrate isobtained in that these two are hardened against each other. For example,a top layer of synthetic material can be hardened on an already foamedsynthetic material board or vice versa, or a top layer of syntheticmaterial can be hardened while said synthetic material board is foamedagainst this hardening top layer or vice versa, or the syntheticmaterial board and at least a portion of the top layer can be extrudedtogether, namely, coextruded. According to a variant, said top layer canalso be glued to the substrate, for example, with contact glue.According to another variant, the top layer and the substrate can bewelded to each other, for example, in that they both are heated andpressed against each other. Herein, the heating preferably is performedat least on the sides of the top layer and the substrate which have tobe adhered to each other. To this aim, for example, heating withinfrared radiation can be chosen.

It is clear that the entire layer composition of the floor panel can beobtained by a combination of the possibilities or variants thereformentioned herein. Namely, the top layer as such can consist of differentlayers, which each as such are provided on the substrate or anotheradjoining layer according to any of these possibilities.

Preferably, said top layer has a higher density than said substrate, orat least a density of more than 500 kilograms per cubic meter. By usinga top layer of high density, nevertheless a substrate consisting of afoamed synthetic material layer of lower density can obtain a goodimpact resistance. The density of said top layer can be adapted, forexample, by the use of filler materials, such as chalk.

It is noted that within the scope of the invention the foamed syntheticmaterial substrate can be provided with filler materials, such as chalk,wood fiber, sand and the like. In such embodiment, savings on the amountof synthetic material can be obtained.

According to a particular preferred embodiment, said top at layer assuch of at least a back layer, a motif or pattern provided thereon, anda transparent or translucent wear layer. Said back layer preferably hasa thickness which is 45 percent or more of the overall thickness of thetop layer. Such back layer preferably consists of a vinyl compound orpolyurethane compound, wherein preferably use is made of fillers, suchas chalk. The synthetic material applied therewith preferably comprisesrecycled synthetic material or substantially consists thereof.Preferably, the back layer is made with a higher density than the wearlayer. Amongst others, to this aim the application of filler materialsin the back layer is of interest. As aforementioned, for the motif orthe pattern, use can be made of a printed material sheet, such as asynthetic material film or a print performed directly on the substrate.For said translucent or transparent wear layer, preferably use is madeof a vinyl layer or polyurethane layer having a thickness of at least0.2 millimeters and still better having a thickness of at least 0.3millimeters.

Preferably, this translucent or transparent layer is made not thickerthan 1 millimeter. By means of a transparent layer of 0.25 to 0.7millimeters, a wear resistance can be obtained which is comparable tothat of laminate floor panels. The transparent or translucent layer caneither be applied as a film, whether or not together with theaforementioned printed film, or can be applied in liquid form andsubsequently be hardened on the substrate. Preferably, the transparentor translucent layer has a thickness which corresponds to at least 25percent of the overall thickness of the top layer. Optionally, the toplayer can include a surface layer on the basis of a UV-hardenedsubstance.

It is noted that according to the above particular embodiment, the backlayer, the motif and the wear layer can be manufactured according tovarious possibilities. According to a first possibility, originally theyall are made as a synthetic material layer, which, for example, arebonded to each other at least with the use of heat. This bond can beobtained, for example, in a heated press device, such as in ashort-cycle press. Subsequently, such composed layer can be adhered tothe substrate, for example, by means of an adhesive connection or bymeans of a welding connection, wherein the substrate and the top layerare melted together. According to a second possibility, at least theback layer and/or the wear layer are provided in liquid or paste-likeform on a carrier material, such as glass fiber non-wovens, where theyharden. According to this second possibility, the motif then either canbe provided by means of a separate printed film, or can be printeddirectly on the back layer or on the bottom side of the wear layer, forexample, by means of offset printing or inkjet printing, preferably bymeans of UV-based inks or solvent inks.

Preferably, said floor panel has a thickness of 5 to 10 millimeters,wherein said top layer as such has a thickness of 0.5 to 3 millimeters.

As aforementioned, the floor panel of the invention is intended inparticular for composing floating floor coverings. To this aim, thefloor panel of the invention comprises preferably at least at twoopposite edges coupling means, with which two of such floor panels canbe locked to each other in horizontal direction as well as in verticaldirection. Preferably, herein this relates to coupling means of the typeknown as such from WO 97/47834. Preferably, said coupling meanssubstantially are made as a tongue-in-groove coupling, which is providedwith locking means or locking parts, wherein said tongue-in-groovecoupling realizes said vertical locking, whereas said locking means orparts are provided for realizing said locking in horizontal direction.

Preferably, said coupling means substantially are realized in saidfoamed synthetic material board. Preferably, said coupling means areprovided by means of a milling treatment with rotating milling tools.Preferably, the floor panel of the invention relates to a rectangular,either oblong or square, panel, which, at both pairs of opposite sides,is provided with mechanical coupling means.

According to a particular embodiment, the floor panel, at least at twoopposite edges, for example, at the long edges of an oblong floor panel,and preferably at all opposite edges, is provided with a recessed edgehaving, for example, the shape of a chamfer. Such chamfer preferably islimited in depth to the thickness of said transparent or translucentlayer. In the case that a deeper recessed edge is intended, the surfaceof the recessed edge can be provided with a separate decorativecovering, or the color and/or the appearance of a possible back layerand/or the substrate can be adapted to the desired effect to beobtained. Said recessed edge preferably is realized by removing amaterial portion on the respective edges. As an alternative, they canalso be realized by means of a deformation exerted at the location ofthe edge material.

According to an alternative for the above particular embodiment, saidrecessed edge also be provided respectively on one edge of a pairopposite edges.

According to a second independent aspect, the present invention relatesto a method for manufacturing panels, wherein these panels comprise atleast a substrate and a top layer provided on said substrate, whereinsaid top layer comprises a thermoplastic, translucent or transparentlayer, with the characteristic that said method comprises at least thefollowing steps:

the step of providing said top layer, including said thermoplasticlayer, on the substrate; the step of heating at least said thermoplasticlayer; and

the step of structuring said thermoplastic layer at least by means of amechanical press element.

It is clear that according to the second aspect of the invention, saidthermoplastic layer as such, before being heated, already islayer-shaped. Preferably, said heating relates to heating from atemperature of less than 100° C. to a temperature of more than 100° C.Preferably, a temperature of minimum 120° C. and still better minimum130° C. is obtained. Preferably, the temperature does not rise above175° C. Preferably, said thermoplastic layer, before being heated, has atemperature of less than 60° C. and still better of less than 40° C.and/or is it not in a paste-like form.

For heating said thermoplastic layer, use can be made of a radiationsource, preferably infrared light. As an alternative, also one or morehot-air ovens or hot-air pistols can be applied.

It is clear that the method of the second aspect preferably is appliedfor realizing the floor panels of the first aspect. Generally, it canalso be applied, independently from the substrate material, for floorpanels where such top layer, or at least said thermoplastic layer,substantially consists of a vinyl compound or a polyurethane compound.For examples of such top layers, also reference is made to the preferredfirst aspect, wherein then again not necessarily use is made of a foamedsynthetic material board. Instead, use can be made of other syntheticmaterial boards or of wood-based substrates, such as MDF or HDF, or ofmineral boards, such as plasterboards. In any case, according to thesecond aspect, use preferably is made of a substrate having an averagedensity of more than 450 kilograms per cubic meter, with a thicknesssituated between 5 and 12 millimeters, such that a sufficientdimensional stability is obtained.

Preferably, for the step of structuring, use is made of a press deviceof the cyclic type, more particular the short-cycle type; in Germanbetter known as a Kurztaktpresse. It is not excluded that the pressdevice is applied for the step of heating the thermoplastic layer.Preferably, however, said heating of the thermoplastic layer isperformed at least partially and preferably substantially or entirelyprior to the press treatment. Instead of a Kurztaktpresse, use can alsobe made of a multiple-opening press, wherein then a plurality ofthermoplastic layers are structured during the same press cycle.

Preferably, said press device is not heated. In other words, the pressdevice preferably is applied at ambient temperature, wherein it is notexcluded that the press element, by the contact with the surface of thethermoplastic layer to be structured, increases its temperature. Theinventors have found that such method reduces the risk of deformationsof the product. Moreover, such method results in a lower risk of thespringing-back of the thermoplastic layer, such that sharp structuraldetails can be realized.

When a heated press device is applied, such heated press cyclepreferably is followed by a cold press cycle, whether or not performedin the same press device. If it is not performed in the same pressdevice, preferably at least the same structured press element isapplied. In this manner, problems with registering between two presselements can be avoided. For example, the thermoplastic layer with thepress element provided thereon can be brought from one to the otherpress device as one stack, without interrupting the contact between thepress element and the thermoplastic layer. It is noted that with aheated press cycle, preferably a temperature of more than 100° C. isreached at the surface of the thermoplastic layer, whereas with a coldpress cycle preferably a temperature of less than 60° C. is reached atthe surface of the thermoplastic layer.

According to a variant, the press element can be provided on thethermoplastic layer before the whole unit of at least the press elementand the thermoplastic layer is fed into the press device. In suchmethod, the thermoplastic layer, prior to the press treatment, can be atleast partially heated in that the press element is heated. The heatingor warming up of the press element can be performed, for example, byapplying magnetic induction. In such method, it is possible to exclude aseparate heating of the thermoplastic layer. As aforementioned, saidpress device preferably as such is not or almost not heated, such that acooling down of the thermoplastic layer is obtained and the risk ofspringing back of the layer is minimized.

Preferably, a pressure of the press between 20 and 65 bar is applied,wherein a pressure of approximately 40 bar is a good value.

Preferably, pressing is performed during 12 to 60 seconds, still betterduring 15 to 30 seconds, and such preferably in the case of a pressdevice of the short-cycle type.

Preferably, as the press element a flat press element or a so-calledpress platen is applied, which is provided with a structure. Such presselement can be manufactured, for example, of metal, namely, a steelalloy, a copper alloy or an aluminum alloy, wherein the structure thencan be obtained, for example, by means of etching, laser and/or millingtreatments. As an alternative, use can also be made of press elements onthe basis of synthetic material, for example, on the basis of melamineor Perspex (PMMA).

It is noted that a method wherein a press element on the basis ofmelamine or another thermo-hardening synthetic material is applied forstructuring a thermoplastic layer, as such forms an independentinventive idea of the present patent application. Such press element assuch can consist, for example, of one or more material sheets providedwith such thermo-hardening synthetic material, such as paper layers,which are consolidated in a press device. The structure of such presselement can be realized in any manner, for example, in that this presselement as such is consolidated by means of a structured press elementof metal, which, by means of etching, laser, and/or milling treatments,is provided with a relief. The advantage of such method is that themetal press element shows almost no wear, whereas the actual presselement on the basis of a thermo-hardening synthetic material is cheapand can be considered a disposable tool. It is clear that the presselement of this inventive idea preferably relates to a flat presselement, or example, a press element for use in a press device of thecyclic type, in a Kurztaktpresse or in a multiple-opening press. Thepress element of the invention can be applied in an ideal manner inpress treatments in which the press device does not have to be heated.In those applications, the reduced heat transfer of the thermo-harder isof no importance. In applications where heat transfer indeed is ofimportance, possibly additives in the thermo-harder can be used, whichimprove the heat conduction thereof, such as, for example, the additionof metal particles, carbon particles and the like. The inventors havefound that a thermo-harder shows ideal detachment properties whenproviding a thermoplastic layer with a structure. Moreover, athermo-harder can be provided with a sharp structure, such that thefreedom of design does not have to be restricted.

Preferably, during the step of warming up, at least a pattern or motif,for example, a printed decor film, is situated on the lower side of saidthermoplastic layer. Such method allows that in a smooth manner astructure can be obtained, which corresponds to the pattern or themotif. To this aim, a relative positioning between at least the patternand the press element can be performed. Still better, the step ofapplying said top layer on the substrate is performed prior to orpossibly at the same time with the step of heating up the thermoplasticlayer. In such case, said press treatment preferably is performed astack comprising at least the substrate and the top layer, includingsaid thermoplastic layer. In the case of a multiple-opening press, thena plurality of such stacks are present in the same press, respectivelyseparated by one or more structured press elements.

It is also noted that said top layer further can also comprise an UVsurface coating. Such coating can be intended, for example, forobtaining a resistance against stains, in particular resulting from shoesoles, on the surface of the floor panel. Preferably, such surfacecoating is applied after said pressing step. Namely, the inventors havefound that such surface coating results in an inferior pressing process.

It is clear that the structure, which according to the second aspect isprovided in the surface of the thermoplastic layer, relates to adecorative relief, such as, for example, a relief imitating wood. Suchrelief can consist, for example, of separate impressions, which imitatewood pores and which together form a structure with the appearance of awood nerve. Preferably, a plurality of such wood pores follow a woodnerve depicted in the motif. Of course, other structures can berealized, too, such as stone structures.

According to a third independent aspect, the present invention alsorelates to a method for manufacturing the floor panels of the firstaspect and/or the preferred embodiments thereof, with the characteristicthat this method comprises at least the steps of manufacturing saidsynthetic material board and of providing said top layer on thissynthetic material board, wherein these two steps are performedcontinuously on the same production line. Preferably, herein saidsynthetic material board is extruded. The third aspect of the inventionprovides for an extremely smooth production process for such floorpanels.

Preferably, the top layer is at least partially obtained from polyvinylchloride (PVC) or other vinyl compounds. According to a firstpossibility for this, it can be started from extruded PVC, which, viaheated rollers, is placed as a layer-shaped substance on a carriermaterial and hardens there. Herein, the carrier material either cancomprise said synthetic material board, or can comprise a separatecarrier material, such as a glass fiber cloth. Preferably, the carriermaterial is heated. Possibly, in said vinyl compounds use can be made ofplasticizers, such as phthalate plasticizers isosorbide plasticizers,and/or of waxes, for obtaining a smoother process. According to a secondpossibility hereof, it can be started from one or more vinyl-containingsynthetic material films, which are adhered to the synthetic materialboard, preferably after supplying heat.

Preferably, on the production line of the third aspect, larger boardsconsisting of foamed synthetic material layers with top layers areformed, from which afterwards, by means of at least a dividingoperation, such as a sawing operation, a plurality of floor panels canbe obtained.

Of course, the method of the third aspect can be combined with a methodhaving the characteristics of the second aspect.

According to all aspects, the present invention relates to floor panelsor other panels, which as such are rigid and thus as such can not bewound up. Preferably, the final panel shows a thickness of more than 5millimeters, however, preferably less of than 15 millimeters. A goodvalue for the thickness is 7 to 10 millimeters. Such panels are verysuitable for providing mechanical coupling means thereon, which allow tocouple two or more such panels at their edges to each other. Preferably,herein use is made of mechanical coupling means, such as of the typeknown from WO 97/47834. It is clear that also the possible largerboards, from which a plurality of such floor panels are formed, and thesubstrates as such are rigid. Preferably, the floor panels, boards andsubstrates are so rigid that they will bend less than 10 centimeters permeter under their own weight.

BRIEF DESCRIPTION OF THE DRAWINGS

With the intention of better showing the characteristics of theinvention, hereafter, as an example without any limitative character,some preferred embodiments are described, with reference to theaccompanying drawings.

FIG. 1 in perspective represents a floor panel according to anon-limiting embodiment of the invention.

FIG. 2, at a larger scale, represents a cross-section according to theline II-II represented in FIG. 1.

FIG. 3 schematically represents a method for manufacturing floor panels.

FIG. 4, at a larger scale, represents a cross-section according to theline IV-IV represented in FIG. 3.

FIGS. 5 to 7, in a view similar to that of FIG. 3, represent variants ofa method for manufacturing floor panels.

DESCRIPTION OF NON-LIMITING EMBODIMENTS

FIG. 1 represents a floor panel 1 for forming a floating floor covering.

FIG. 2 clearly shows that the floor panel 1 is of the type whichcomprises at least a substrate 2 and a top layer 3 provided on thissubstrate 2, wherein the top layer 3 comprises a motif 4, in this case awood motif.

In the example of FIGS. 1 and 2, this relates to a rectangular floorpanel 1, which, at the first pair 5-6 as well as at the second pair 7-8of opposite edges, is provided with mechanical coupling means 9.

FIG. 2 represents that the coupling means 9 at the first pair 5-6 ofopposite edges, namely, the long edges of the floor panel 1,substantially are performed as a tongue 10, a groove 11, respectively.Herein, the groove 11 is flanked by an upper lip 12 and a lower lip 13.When two of such floor panels 1 are coupled to each other at these edges5-6, the cooperation of the tongue 10 and the groove 11 as such leads toa locking in a vertical direction V1 perpendicular to the plane of thefloor panels 1. The cooperation between the tongue 10 and the groove 11preferably comprises forming one or more pairs 14-15-16-17 of verticallyactive locking surfaces. In this case, a pair of locking surfaces 14-15is formed between the upper surface of the tongue 10 and the lower sideof the upper lip 12 and a pair 16-17 between the lower side of thetongue 10 and the upper side of the lower lip 13. At least one of saidpairs 14-15, and in this case both pairs 14-15-16-17 of verticallyactive locking surfaces are formed in the example of the particularsubstrate 2 of the invention. In this manner, a strong locking invertical direction V1 is obtained.

The coupling means 9 represented here also comprise locking means orlocking parts 18-19, which result in a locking in a horizontal directionH1 perpendicular to the coupled edges 5-6 and in the plane of thecoupled floor panels 1. In the example, the locking parts 18-19 areformed as an upstanding part 19 on the lower lip 13 and a recess 18 onthe lower side of the tongue 10. These locking parts 18-19 are providedin each other when coupling two or more of such floor panels 1. Herein,one or more, preferably two, pairs 20-21-22-23 of horizontally activelocking surfaces are created. In the example, one pair of horizontallyactive locking surfaces 20-21 is situated on said upstanding part 19 andcooperating therewith surface 20 of said recess 18. This pair ofhorizontal locking surfaces 20-21 is formed from the material of theparticular substrate 2 of the invention. The respective locking surfaces20-21 are oriented at an angle A with the surface of the floor panels 1.This angle A preferably is more than 30 degrees, and still better morethan 45 degrees. Angles A of 90 degrees or more are not excluded. Thesecond pair of horizontal locking surfaces 22-23 of the example issituated next to the floor surface, at the height of the location wherethe top layers 3 of two floor panels, which are coupled to each other,are flanking each other. In this case, this second pair of lockingsurfaces 22-23 is made substantially vertical. Moreover, this pair ofhorizontally active locking surfaces 22-23 is substantially and hereeven exclusively formed of the material of the top layer 3.

Many of the characteristics listed up above and represented in FIGS. 1and 2 can be applied, within the scope of the invention, broader than incombination with the other characteristics of the example. The followingcharacteristics, each individually or in any combination, can offerinteresting advantages:

-   -   the characteristic that the coupling means 9 offer a locking in        horizontal direction H1 as well as in vertical direction V1,        independently from the fact whether the coupling means 9 are        mechanical and/or are performed, whether or not substantially,        in the form of a tongue 10 and groove 11;    -   the characteristic that at least one pair of horizontally active        locking surfaces 20-21 of the coupling means 9 is realized in        the substrate 2 of the invention and/or the characteristic that        at least one pair of horizontally active locking surfaces 22-23        of the coupling means 9 is at least partially and preferably        entirely realized in the top layer 3;    -   the characteristic that one or more pairs 14-15-16-17 of the        vertically active locking surfaces are formed at least partially        and preferably entirely from the substrate 2;    -   the characteristic that the mechanical coupling means 9 consist        of milled profiles, which, for at least 70 percent of their        circumference, are provided in the substrate 2 of the invention;    -   the characteristic that the first pair of opposite edges 5-6 as        well as the second pair of opposite edges 7-8 is provided with        coupling means;    -   the characteristic that the mechanical coupling means 9 allow a        coupling by means of a turning movement W along the respective        edges 5-6 and/or a horizontal shifting movement S of the edges        towards each other and/or a downwardly directed movement of a        male coupling part having for example, a tongue 10, into a        female coupling part having, for example, a groove 11;    -   the characteristic that the lower lip 13 extends in horizontal        direction beyond the upper lip 12;    -   the characteristic that in a coupled condition of two of such        floor panels 1 a tension force is obtained between the top        layers 3 of the respective floor panels 1;        herein, the lower lip 13 preferably is in a bent condition;    -   the characteristic that the lower lip 13, in a coupled        condition, is bent.

The particularity of the present invention, at least according to itsfirst aspect, consists in that said substrate 2 substantially consistsof a foamed synthetic material board. In the example, the substrate 2relates to a foamed PVC board of the closed cell type. The board 2concerned has an average density of 450 kilograms per cubic meter,however, also has a local density on both flat sides 24-25, namely, adensity of 500 kilograms per cubic meter or more, which is higher thanthe density of a central layer 26 of the synthetic material board 2.Moreover, the substrate 2 comprises separate layers 27, in this caselayers of glass fiber, which increase the bending stiffness thereof. Inthe example, these separate layers 27 are situated on both flat sides24-25 of the substrate 2.

The top layer 3 of the floor panel 1 of the example is a top layer 3which substantially consists of synthetic material, namely, of a vinylcompound such as PVC (polyvinyl chloride). This top layer 3 has a higherdensity than the average density of the substrate 2. The represented toplayer 3 as such consists of a back layer 28, a provided thereon motif 4and a transparent wear layer 29. The back layer 28 is the thickest anddensest layer of the top layer 3. It consists of recycled syntheticmaterial, here PVC, which comprises filler material, preferably chalk.For said motif 4, use is made of a printed synthetic material film 30.For example, use can be made of a synthetic material film 30 which isprinted by means of solvent inks. Such inks may result in ahigh-resolution print quality. The synthetic material film 30 as suchcan consist of PVC or another vinyl compound. For the transparent layeror wear layer 29, use is made of vinyl, such as PVC.

Preferably, said transparent layer 29 is free from filler materials orhard particles, such as aluminum oxide. The inventors have found that atransparent or translucent layer 29 of 0.2 millimeters of vinyl as suchis sufficient for obtaining an acceptable wear resistance. Of course, itis not excluded that use should be made of a wear layer 29 whichcomprises hard particles. However, these have a negative influence onthe transparency of such wear layer and lead to accelerated wear ofmachines which are applied when manufacturing such floor panels 1. Whenhard particles are applied, preferably a wear layer 29 is used having athickness of less than 0.3 millimeters, or even less than 0.2millimeters. Preferably, in such case use is made of hard particles in aconcentration of 5 to 20 grams per square meter, wherein 10 grams persquare meter represent a good value. Preferably, the applied hardparticles have an average grain size between 30 and 120 micrometers, andstill better between 50 and 90 micrometers.

As is mentioned in the introduction, however, not represented here, thefloor panel 1 can be provided with a surface layer at its surface, forexample, on the basis of a UV-hardened substance. Such layer preferablyhas a thickness of less than 0.1 millimeter, or still better of lessthan 50 micrometers. It is not excluded that such surface layer includeshard particles, such as aluminum oxide particles, wherein these hardparticles preferably have an average grain size of less than 50micrometers. Possibly, flat particles may be used here.

In dashed line 31, it is represented on FIG. 2 that a backing layer 32can be provided on the lower side of the floor panel 1. Such backinglayer 32 preferably consists of a similar material as the top layer 3,for example, of vinyl, which possibly is provided with filler material.Preferably, the density of said backing layer 32 is lower than thedensity of said top layer 3, or anyhow at least lower than the backlayer 28, which in the example is included in said top layer 3.Preferably, the backing layer 32 consists of open cell foamed PVC orso-called cushion vinyl (cushion vinyl). Such backing layer 32 can beconnected to the substrate by similar methods as the top layer 3,namely, either by gluing, by foaming it against the substrate or viceversa, by melting or by extruding or otherwise forming this backinglayer 32 together with said synthetic material board 2.

FIG. 3 represents a method for manufacturing floor panels 1 inaccordance with the embodiment of FIGS. 1 and 2. Herein, larger boardsare formed, which show the composition of such floor panel 1 and which,in a step not represented here, are divided into panels showingapproximately the final dimensions of such floor panel 1. After thisstep of dividing, still further operations can be performed on thesepanels 1, such as forming coupling means or coupling parts 9 at theedges thereof.

The method comprises a step S1 where in the top layer 3 is provided onthe substrate 2, and a step S2 wherein a thermoplastic translucent ortransparent layer 29, which forms part of the top layer 3, is structuredby means of a mechanical press element 33. In the example of FIG. 3,these two steps S1-S2 are performed simultaneously in a press device 34,for example, as represented here, in a press device 34 of theshort-cycle type. As press element 33, a press platen is applied.

FIG. 4 clearly shows that this press platen 33 is provided with astructure 35 which is copied by means of the press treatment at leastinto thermoplastic transparent or translucent layer 29. In this case,the underlying motif 4 and the back layer 28 are deformed as well.However, it is also possible that the motif 4 and/or the back layer 28are left undisturbed during the press treatment, or that, in otherwords, the impressions 36 which are formed in the thermoplastic layer 29are limited in depth, such that at least the motif 4, or the printedsynthetic material film 30, is free from local deformations.

Preferably, by means of the step S2 of structuring, impressions 36 areobtained which in location and/or size correspond to the motif 4.

Prior to the press treatment, a step S0 is performed, wherein twothermoplastic layers 29-30 are adhered to each other. Namely, thesynthetic material film 30 and the transparent thermoplastic layer 29are welded or melted to each other by means of a calender device 37. Tothis aim, use is made of infrared heating 38 and one or more rollers 39.The obtained whole is cut to sheets 41 by means of the cutting tool 40and, together with the back layer 28, the substrate 2 and a backinglayer 32, is brought into the press device 34.

During said press treatment, a third step S3 is performed, too. Herein,the thermoplastic translucent or transparent layer 29 is heated again,by which providing a structure by means of the press element 33 becomespossible. Moreover, by means of this heat an adherence of thethermoplastic layer 29, the synthetic material film 30, the back layer28, the substrate 2 and the backing layer 32 is obtained. Preferably,the hot press cycle is followed by a cold or cooled press cycle, whetheror not taking place in the same press device 34. Such cool cycleprevents an excessive springing back of the realized structure ofimpressions 36.

According to a not represented variant of FIG. 3, the thermoplasticlayer 29 can be sufficiently heated prior to the press treatment, forexample, by means of the represented infrared heating 38, such that itcan be fed into the press device 37 in warm condition. In such case, acold press cycle may suffice for structuring the thermoplastic layer 29.The adherence between this thermoplastic layer 29, the back layer 28,the substrate 2 and the possible backing layer 32 then preferably isobtained in another manner than by means of the cold press treatment.

FIG. 5 represents a variant, wherein the thermoplastic layer 29 isprovided on the substrate 2 prior to the step S2 of providing astructure. Schematically, a calender device 37 is represented by whichthe thermoplastic layer 29 and the possible backing layer 32 are adheredto the substrate 2. It is clear that also a possible printed syntheticmaterial film 30 and/or back layer 28, for example, also by means ofsuch device 37, can be provided on the substrate 2 prior to the step S2of providing a structure. In this case, the complete layer composition2-3-32 of the floor panel 1 is obtained prior to the step S2 ofproviding a structure.

In accordance with the second aspect of the invention, in FIG. 5 thethermoplastic layer 29 is heated, in this case prior to the step S2 ofproviding a structure, by means of one or more infrared heating units38. The thermoplastic layer 29, while it already forms part of theconnected whole of substrate 2, top layer 3 and possible backing layer32, is fed in its hot condition into the press device 34, where it isprovided with impressions 36 by means of a press element 33. Preferably,here a cold press cycle is used. A similar result can be achieved asrepresented in FIG. 4.

FIG. 6 represents another variant, wherein the thermoplastic transparentor translucent layer 29 is formed in line with the step S1 of providingat least this thermoplastic layer 29 on the substrate 2. To this aim, anextruding machine 42 is installed above a pair of heated rollers 43. Bymeans of the extruding machine 42, amounts of vinyl are provided betweensaid heated rollers 43 and applied in paste-like form on a web-shapedcarrier material 44, where it hardens. The carrier material 44 as suchcan be heated, for example, by means of one or more infrared heatingunits 38. The carrier material 44 preferably comprises a printedsynthetic material film 30, which shows the motif 4 of the final floorpanel 1. The extruded vinyl forms a thermoplastic transparent ortranslucent layer 29 above the motif 4. It is clear that in a similarmanner also the back layer 28 and/or the backing layer 32 can be formedagainst the substrate 2. The step S1 of applying the thermoplastic layer29 on the substrate 2, the step S3 of heating the thermoplastic layerand the step S2 of providing a structure in this example are performedin a similar manner as in the embodiment of FIG. 5.

It is possible that the thermoplastic layer 29 is provided with astructure at least partially prior to the step S1 of applying this layer29 on the substrate 2. To this aim, for example, a structured roller 45can be applied.

In the example of FIG. 6, use is made of a method having thecharacteristics of the third aspect of the invention. To this aim, thestep of manufacturing the synthetic material board 2 and the step S1 ofproviding the top layer 3 on this synthetic material board 2, or atleast providing at least a portion or a partial layer 28-29-30 thereof,for example, the transparent or translucent synthetic material layer 29,are performed continuously and on the same production line. In thiscase, the synthetic material board 2 is manufactured by means of anextrusion process, which makes use of an extruding machine 46.

FIG. 7, too, represents an embodiment having, amongst others, thecharacteristics of the second and the third aspect of the invention. Inthis case, the vinyl originating from the extruding machine 42 isprovided in past-like form directly on the substrate 2, namely, withoutthe intermediary of a carrier material. Of course, in such examplealready one or more other partial layers 28-29-30 of the top layer 3 canbe provided on the substrate 2, such as, for example, a back layer 28and/or a motif 4, for example, in the form of a printed syntheticmaterial film 30. For the rest, the process represented here is similarto that represented in FIGS. 6, 7 and 8.

According to an alternative, which is not represented here, thesubstrate 2 and one or more partial layers 28-29-30 of the top layer 3and/or the backing layer 32 are extruded together via so-calledcoextrusion. Preferably, in such case at least the back layer 28 and/orthe backing layer 32 are extruded together with a synthetic materialboard 2, preferably a foamed synthetic material layer, such as describedby means of the first aspect of the invention.

It is clear that the method illustrated in FIGS. 3 to 7 shows examplesof a method having the characteristics of the second aspect of theinvention. FIGS. 6 and 7 also are examples of the third aspect of theinvention.

According to the embodiments of FIGS. 5, 6 and 7, the substrate 2 issupplied as an endless board material, which is divided prior to thestep S2 of providing a structure. However, it is not excluded that inthese embodiments, too, boards of limited length are applied, forexample, a length approximately corresponding to the length of aninteger of the final floor panels, for example, corresponding to one tofour times this length. It is also possible that the board material fromFIGS. 3, 5, 6 and 7, in endless form, is at least subjected to step S2of providing a structure. In such embodiment, preferably a press deviceis applied of the continuous type. Of course, in such case the cuttingdevice 40 preferably is arranged after the press device.

It is clear that the infrared heating units 38, as mentioned and/orrepresented in connection with the figures, can be replaced by any otherheating apparatus. According to a particular variant, the press element33 is provided on the thermoplastic layer 29 prior to the step S2 ofproviding a structure and this press element 33 is heated, wherein theheating of the thermoplastic layer 29 then occurs at least partially bythe contact with the press element 33. In the case of a metallic presselement 33, the warming up of the press element 33 can be performed bymeans of magnetic induction.

The present invention is in no way limited to the embodiments describedherein above, on the contrary, such methods and floor panels can berealized according to various variants, without leaving the scope of thepresent invention. Moreover, the panels, instead as floor panels 1, mayalso be realized as wall panels or ceiling panels or even as furniturepanels. Of course, the methods of the invention, mutatis mutandis, canbe applied for manufacturing wall panels, ceiling panels, furniturepanels or the like.

1. A floor panel comprising: a substrate; and a top layer located aboveand glued to the substrate; wherein the substrate includes a foamed PVCboard with fillers; wherein the foamed PVC board has an average densityof more than 300 kilograms per cubic meter; wherein the top layerincludes a back layer, a printed synthetic material film located abovethe back layer and a transparent or translucent synthetic material wearlayer located above the printed synthetic material film; wherein theback layer includes a vinyl compound with fillers; wherein the backlayer has a thickness of at least 45 percent of the thickness of the toplayer; wherein the floor panel includes a first pair of edges and asecond pair of edges; wherein the floor panel includes first mechanicalcoupling parts at the first pair of edges and second mechanical couplingparts at the second pair of edges; wherein the first mechanical couplingparts allow a horizontal and vertical locking of two of such floorpanels using a turning movement along the respective edges; wherein thefirst mechanical coupling parts include a tongue and a groove; whereinthe groove is flanked by an upper lip and a lower lip; wherein the firstmechanical coupling parts include a vertical locking mechanism having avertically active locking surface at the upper side of the tongue and avertically active locking surface at the lower side of the upper lip;wherein the first mechanical coupling parts include a horizontal lockingmechanism having a horizontally active locking surface at the lower sideof the tongue and a horizontally active locking surface at the upperside of the lower lip; and wherein both said horizontally active lockingsurfaces and both said vertically active locking surfaces are formedcompletely in the material of the foamed PVC board.
 2. The floor panelof claim 1, wherein at least 70 percent of the circumference of thefirst mechanical coupling parts is formed in the material of the foamedPVC board.
 3. The floor panel of claim 1, wherein the first mechanicalcoupling parts comprise additional horizontally active locking surfacessituated at the height of the location where the top layers of two ofsuch floor panels in coupled condition are flanking each other; andwherein the additional horizontally active locking surfaces are formedsubstantially in the material of the top layer.
 4. The floor panel ofclaim 1, wherein the first mechanical coupling parts comprise additionalvertically active locking surfaces at the lower side of the tongue andthe upper side of the lower lip, respectively; and wherein theadditional vertically active locking surfaces are formed completely inthe material of the foamed PVC board.
 5. The floor panel of claim 1,wherein the substrate has a thickness of at least 5 millimeters.
 6. Thefloor panel of claim 1, wherein the foamed PVC board has a top flat sideand a bottom flat side; and wherein the foamed PVC board has a localdensity on the top flat side which is higher than in a central layer ofthe foamed PVC board.
 7. The floor panel of claim 6, wherein the foamedPVC board has a local density on the top flat side and the bottom flatside which is higher than in a central layer of the foamed PVC board. 8.The floor panel of claim 1, wherein the transparent or translucentsynthetic material wear layer comprises a vinyl layer.
 9. The floorpanel of claim 1, wherein the back layer is the thickest and densestlayer of the top layer.
 10. The floor panel of claim 1, wherein the toplayer has a thickness of 0.5 to 3 millimeters.
 11. The floor panel ofclaim 1, wherein the top layer has a density of more than 500 kilogramsper cubic meter.
 12. The floor panel of claim 1, wherein the top layerhas a higher density than the substrate.
 13. The floor panel of claim 1,wherein the floor panel comprises a backing layer below the substrate.14. The floor panel of claim 13, wherein the backing layer has a lowerdensity than the back layer.
 15. The floor panel of claim 1, wherein thefloor panel has a thickness of 5 to 10 millimeters.
 16. The floor panelof claim 1, wherein the floor panel is rectangular and oblong andincludes a pair of long edges and a pair of short edges; wherein thepair of long edges is formed by the first pair of edges; and wherein thepair of short edges is formed by the second pair of edges.
 17. The floorpanel of claim 1, wherein the floor panel will bend less than 10centimeters per meter under its own weight.
 18. The floor panel of claim1, wherein the foam of said foamed PVC board comprises chambers whichare practically not interconnected.
 19. A floor panel comprising: asubstrate; a top layer located above and glued to the substrate; and abacking layer located below the substrate; wherein the substrateincludes a foamed PVC board with fillers; wherein the foamed PVC boardhas an average density of more than 300 kilograms per cubic meter;wherein the foamed PVC board has a top flat side and a bottom flat side;wherein the foamed PVC board has a local density on the top flat sideand the bottom flat side which is higher than in a central layer of thefoamed PVC board; wherein the top layer includes a back layer, a printedsynthetic material film located above the back layer, a transparent ortranslucent synthetic material wear layer located above the printedsynthetic material film and a surface layer located above thetransparent or translucent synthetic material wear layer; wherein theback layer comprises a vinyl compound with fillers; wherein the backlayer has a thickness of at least 45 percent of the thickness of the toplayer; wherein the transparent or translucent synthetic material wearlayer includes a vinyl layer; wherein the surface layer includes a UVhardened substance; wherein the floor panel includes a first pair ofedges and a second pair of edges; wherein the floor panel includes firstmechanical coupling parts at the first pair of edges and secondmechanical coupling parts at the second pair of edges; wherein the firstmechanical coupling parts allow a horizontal and vertical locking of twoof such floor panels using a turning movement along the respectiveedges; wherein the first mechanical coupling parts include a tongue anda groove; wherein the groove is flanked by an upper lip and a lower lip;wherein the first mechanical coupling parts include a vertical lockingmechanism having a vertically active locking surface at the upper sideof the tongue and a vertically active locking surface at the lower sideof the upper lip; wherein the first mechanical coupling parts include ahorizontal locking mechanism having a horizontally active lockingsurface at the lower side of the tongue and a horizontally activelocking surface at the upper side of the lower lip; and wherein bothsaid horizontally active locking surfaces and both said verticallyactive locking surfaces are formed completely in the material of thefoamed PVC board.
 20. The floor panel of claim 19, wherein the substratehas a thickness of at least 5 millimeters.
 21. The floor panel of claim19, wherein the back layer is the thickest and densest layer of the toplayer.
 22. The floor panel of claim 19, wherein the top layer has athickness of 0.5 to 3 millimeters.
 23. The floor panel of claim 19,wherein the top layer has a higher density than the substrate.
 24. Thefloor panel of claim 19, wherein the top layer has a density of morethan 500 kilograms per cubic meter.
 25. The floor panel of claim 19,wherein the backing layer has a lower density than the back layer. 26.The floor panel of claim 19, wherein the floor panel has a thickness of5 to 10 millimeters.
 27. The floor panel of claim 19, wherein the floorpanel is rectangular and oblong and includes a pair of long edges and apair of short edges; wherein the pair of long edges is formed by thefirst pair of edges; and wherein the pair of short edges is formed bythe second pair of edges.
 28. The floor panel of claim 19, wherein thefloor panel will bend less than 10 centimeters per meter under its ownweight.
 29. The floor panel of claim 19, wherein the foam of said foamedPVC board comprises chambers which are practically not interconnected.30. A floor panel comprising: a substrate; and a top layer located aboveand welded to the substrate; wherein the substrate includes a foamed PVCboard with fillers; wherein the foamed PVC board has an average densityof more than 300 kilograms per cubic meter; wherein the top layerincludes a back layer, a printed synthetic material film located abovethe back layer and a transparent or translucent synthetic material wearlayer located above the printed synthetic material film; wherein the toplayer has a thickness of 0.5 to 3 millimeters; wherein the top layer hasa density of more than 500 kilograms per cubic meter; wherein the backlayer comprises a vinyl compound with fillers; wherein the back layerhas a thickness of at least 45 percent of the thickness of the toplayer; wherein the back layer has a higher density than the transparentor translucent synthetic material wear layer; wherein the transparent ortranslucent synthetic material wear layer has a thickness of 1millimeter or less; wherein the floor panel is rectangular and oblongand includes a pair of long edges and a pair of short edges; wherein thefloor panel includes first mechanical coupling parts at the pair of longedges and second mechanical coupling parts at the pair of short edges;wherein the first mechanical coupling parts allow a horizontal andvertical locking of two of such floor panels using a turning movementalong the respective long edges; wherein the first mechanical couplingparts include a tongue and a groove; wherein the groove is flanked by anupper lip and a lower lip; wherein the first mechanical coupling partsinclude a vertical locking mechanism having a vertically active lockingsurface at the upper side of the tongue and a vertically active lockingsurface at the lower side of the upper lip; wherein the first mechanicalcoupling parts include a horizontal locking mechanism having ahorizontally active locking surface at the lower side of the tongue anda horizontally active locking surface at the upper side of the lowerlip; and wherein both said horizontally active locking surfaces areformed completely in the material of the foamed PVC board.
 31. The floorpanel of claim 30, wherein the foamed PVC board has a top flat side anda bottom flat side; and wherein the foamed PVC board comprises a firstglass fiber layer situated on the top flat side and a second glass fiberlayer situated on the bottom flat side.
 32. The floor panel of claim 30,wherein the floor panel will bend less than 10 centimeters per meterunder its own weight.
 33. The floor panel of claim 30, wherein the foamof said foamed PVC board comprises chambers which are practically notinterconnected.